合成气制二甲醚中残留钠对催化剂的影响

Effect of Na^+on structure and property of catalysts for DME synthesis from syngas

在完全液相法的理论基础上结合共沉淀的方式,通过离心控制洗涤沉淀次数分别为1、2、3、4制备了Cu/Zn/Al催化剂,考察了不同Na^+浓度对合成气一步法制二甲醚(DME)双功能催化剂活性的影响,选用XRD、H2-TPR、ICP、SEM、N2吸附测试、NH3-TPD对所制备催化剂进行表征分析。结果表明,不同洗涤次数对催化剂残留Na^+的相对含量、Cu0晶粒尺寸及分散性、Cu^+的还原难易程度和表面酸量均有较为明显的影响,从而影响催化剂活性。在120 h评价周期内,催化剂活性与洗涤次数呈正相关,其中以洗涤4次制备的催化剂性能最优,CO平均转化率可达71.41%,DME选择性为85.36%。

The Cu/Zn/Al catalysts were prepared by combining the method of co-precipitation on the theoretical basis of the complete liquid phase technology and controlling the washing times of the precipitate to 1,2,3,and 4 times by centrifugation.The effect of Na+content in the catalyst on the activity of the bifunctional catalysts for the one step synthesis of dimethyl ether(DME)from syngas were investigated,and XRD,H2-TPR,ICP,SEM,N2 adsorption,and NH3-TPD were used to characterize the catalysts.The results showed that washing times had a significant effect on the content of residual Na+in catalyst,the crystal size and dispersibility of Cu^0,the ease of reduction of Cu+and the amount of surface acid,thereby affecting the activity of the catalyst.In the 120 h evaluation period,the catalyst activity was positively correlated with the washing times.The catalyst prepared by washing 4 times exhibited the best performance with a CO average conversion of 71.41%and a DME selectivity of 85.36%.